The present invention concerns agricultural machines of the haymaking-machine type for the tedding and/or windrowing of fodder, comprising at least two rotors whose axes form a certain angle with the ground. These rotors are interconnected by a hollow beam or a tube through which there passes a transmission shaft intended to drive the rotors with a rotating movement about the said axes. Such machines, when they are situated in the windrowing position, co-operate with guide elements or windrowing screens situated to the rear of the machine and fixed to the latter by means of arms extending towards the front of the machine.
In order to transform the machines of this kind so that they may move from their tedding position into their windrowing position and conversely, it is generally necessary to effect three distinct operations. In fact the working position of the tools must be modified according to whether it is intended to carry out tedding or windrowing, and the axes of the rotors must be inclined or erected for example by means of a screw/nut system or any other device. Finally the guide elements must be retracted or placed in position for the formation of the windrow. All these operations are impractical in execution since it is necessary to act upon various regions of the machine, involving a certain loss of time. Moreover as the size of the angle of inclination of the rotors is left to the free estimation of the user of the machine, the latter may be induced to proceed by trial and error to find the optimum angle of inclination. This procedure thus is detrimental to the economy of the machines on which the regulation of the angle of action of the rotors is carried out by a hand crank and/or with the aid of the prop of the third point of the hitch device of the tractor driving said machine.